One prior art infrared microphone (a model LT 71) has been provided by Lightspeed Technologies, Inc., for uses, such as in a classroom. Microphones in accordance with this prior art have circuitry that convert a presenter's voice into infrared signal representations thereof and transmits these infrared signals to an infrared receiver. In this known microphone, the microphone is portable and can be worn by the user, such as hung by a cord from the user's neck. Plural LT 71 microphones can be used in the same classroom with each being adjusted to transmit its infrared signals using a different carrier frequency. Modulation of infrared signals is done in the LT 71 with a frequency modulated current source driving one or more LEDs connected either in parallel or in series to a fixed voltage source. This prior art LT 71 microphone runs off of battery power (two double A batteries). Efficiencies of operation are desirable in order to extend battery life and/or to reduce the size and weight of batteries for a given operational time.
A need exists for improved microphone circuitry and related methods for an infrared microphone transmission system.